The 2α-methyl-2β-[(1,2,3-triazol-1-yl)methyl]penam-3α-carboxylic acid ester represented by formula (2)
wherein R is a penicillin carboxyl protecting group, is a compound that is useful, for example, as an intermediate for producing a β-lactamase inhibitor.
The compound that is represented by formula (2) can be produced, for example, by reacting a 2′-halogenated penam compound represented by formula (1)
wherein X represents chlorine or bromine and R is as defined above, with 1,2,3-triazole (see Patent Document 1).
According to the Patent Document 1, a 2′-halogenated penam compound of formula (1) is reacted with 1,2,3-triazole in a solvent such as dimethylformamide, acetonitrile, acetone, tetrahydrofuran, dioxane, methanol, ethanol, etc., under temperature conditions in the range of 0° C. to 60° C.
However, when the 2′-halogenated penam compound of formula (1) is reacted with 1,2,3-triazole as described in Patent Document 1, a large amount of the by-product cepham compound represented by formula (3) is unavoidably generated as an isomer, with the result that the desired 2α-methyl-2β-[(1,2,3-triazol-1-yl)methyl]penam-3α-carboxylic acid ester represented by formula (2) cannot be obtained with a high yield.
wherein R is as defined above.
Therefore, the development of an industrially advantageous process is desired that is capable of remarkably suppressing the generation of the by-product cepham compound of formula (3) to efficiently produce the 2α-methyl-2β-[(1,2,3-triazol-1-yl)methyl]penam-3α-carboxylic acid ester of formula (2). Patent Document 1: Japanese Examined Patent Publication No. 1995-121949